The proposed research is a four-year extension of the High/Scope Foundation's program of longitudinal research, now in its seventeenth year. It has two broad objectives. First it is an investigation of the causes of delinquency among persons raised in poverty. Second it is an investigation of the effects of preschool education on the status and behavior of youths aged 15 and 19 years old. Previous research with this sample has shown that preschool education reduced school failure. Now the two objectives of the proposed research combine to form the following hypothesis; Preschool education for the disadvantaged children, by reducing school failure, will help to reduce juvenile delinquency. The longitudinal sample of 215 persons were originally placed by a random assignment procedure in groups who either attended a preschool program organized by a distinct curriculum model or did not attend preschool at all. They have continually been involved in a schedule of prospective assessment, including a variety of school variables. Current assessments focus on measures of self-reported delinquent behavior and court records of delinquent activity. They also include information on schooling, economic activity, coping ability, and family and community activities. The objectives of the research will be achieved through a plan of data collection and intensive data analysis. The primary data analysis and literature review, moves to formulation and testing of causal model, and then quantitative analysis of individual cases. Two other procedures are also proposed: individual case studies involving further data collection and cost-benefit analysis.